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For many years I have noticed ducting of VHF Noaa Weather Radio stations that generally occur along the Oceanfront anytime during the year but mainly during the spring and summer . This is a common occurrence here at my qth , I am not sure how prevalent these are inland . I will attempt to document the ducting , which is usually caused by the difference in sea and air temps , esp cooler sea temps that are commonly overun by much warmer air some height above the cooler air. This allows the vhf to travel beyond the line of sight , sometimes for hundreds of miles outside normal listening area. This can be all north, all South or both of conditions allow, rarely West. Generally these are best during times of no wind, although not as a strict rule. Radio used is a Unimetrics Seahawk model 24 Marine radio, 12 feet above sea level using only a 12 inch jumper clip as antenna . That way eliminates any possibility of reception due to elevation. The orientation of the wire seems to be more important than the quality of the antenna.These can disappear and reappear at any given minute. Closer stations in the path may not be heard at all.Home station is KHB37 Driver Va on 162.550 mhz.The temps will be for my location. The mileage is straight line or flight distanceI realize this is an obscure and possibly location based DX target , but if you notice any out of area stations please note.

When I lived in Omaha, usually every morning there was a tropoduct along the mighty Missouri river up to Sewer City Ia I mean Sioux City Ia. This was nice as you could use their repeaters and have some fun on the drive to work. The trip home did not have such great tropo as the am drive but did sometimes. It also helped that the hiway I used was pretty much the highest ground between Sioux City and Kansas City or something like that.

The tropoduct seemingly followed the river, so I imagine you will hear many stations along the coastline when the duct starts ducting. When your duct starts getting leaky, just apply more duct tape

I'm listening while driving through downtown, at points one station would completely blanket the other, then vise-versa. Lots of multipath going on in an urban area - anyone who's been to Richmond knows the downtown / central business district area is full of hills and valleys - add that to the steel-and-concrete around you at street level and yeah, VHF does some interesting things. There's a reason most two-way systems in this area are on 450-470 MHz and the public safety system is on 800 MHz (well, they're on 800 MHz because Motorola wants more money, but I digress...)

I can hear NOAA Weather VHF DX basically every morning during my (short) morning commute that starts at roughly 0645 local time. Antenna is a standard NMO mount 1/4 wave VHF antenna mounted on the trunk lip with good condition (read: removed paint) to the chassis of the car. When the band is open I often check the STARS statewide VHF trunking system frequencies for activity, the go-to one being the Fork Mountain, VA control channel (152.7125 MHz) and that was coming in full scale this morning as well.

I used to listen to NOAA weather radio most mornings (prior to the Internet) while getting ready for work. When I heard other stations creeping in I'd get on 146.52 during the commute and usually get some interesting contacts. There were also a couple of repeaters that would be regularly heard during tropo as well.

NOAA is a good indicator for 2m tropo just like TV Ch 2 used to be an indicator that the 6m band was open.

KHB37 out of Virginia Beach, VA and KHB36 out of Manassas, VA often fight each other during the band openings...but I find the "in between" channels - from back when NOAA Weather Radio was only 3 channels 162.400, 162.475 and 162.550 - the in between channels that were added later, 162.425, 162.450, 162.500 and 162.525 are good listening targets since those are the "fill-in" stations. KZZ28 must be on a mountaintop though...because I can hear it with a handheld radio and a stock antenna even when the band is completely closed.

You have the advantage of the ocean - temperature inversion ducting - whereas I only get mine from weather systems. Do you hear the Richmond transmitter ever (WXK65 on 162.475 MHz)? It's located on one of the many towers just south of the James River in Richmond. 1000 watts too.

When I drive to work this morning I'll see if I can hear any early morning ducting

Heard stations on all 7 NOAA Weather Radio frequencies this morning (0645-0655 local time). Heard KHB36 out of Manassas, VA very strong on 162.550. 162.400 had KEC83 (Baltimore, MD) booming through with another station underneath it that I couldn't ID. Also heard WNG588 out of Mount Jefferson, NC on 162.500 but with very severe fading as I drove through downtown. 162.450 had two stations on it, one of them being KZZ28, unable to ID the second. I heard a strong signal on 162.425 and they were discussing the forecast for Northern Virginian Mountain Forecast including Skyline Drive (possible WZ2527 out of Fredericksburg, VA?) no ID heard.

I have signals on all 7 frequencies right now (1524z) which is pretty normal for here. It is interesting that they do not all use the same deviation.

You're also receiving using a discone antenna high up in the air, not a 1/4 wave VHF whip at street level

I think its a question of the age of the transmitter - as they are all specified for regular "wideband" (by land mobile definition) 20 kHz bandwidth (or 25 kHz bandwidth, depending on who you ask) 20K0F3E emission type. I have noticed that NOAA weather radio sounds better on wideband settings on receivers with that capability. The TYT TH-9000D, which is my primary mobile VHF radio, has three FM deviation/bandwidth settings, 25K, 20K and 12K. NOAA Weather Radio sounds best in 25K (wideband), but there is very little difference between that and 20K (middle band). With DX listening, the 20 kHz setting seems to work best. It's perfectly listenable in 12K mode (which is 11K0F3E emission, apparently for Part 90 VHF land mobile compliance).

I put the radio in 25K or 20K mode for 2 meter amateur use and listening to NOAA Weather Radio, but use narrowband for everything else.

I imagine the older NOAA transmitters are pushing more deviation than the newer ones but its harder to say for sure.

On a RS scanner upstairs it's not uncommon to hear all or many of the surrounding stations . The logs above were observed at maybe +13ft sea level to try and kick out anything that would be normal for the antenna at around 25 ft asl.I used a 6 inch jumper for the antenna that could be moved directionally

What distance at 1000 watts would you guys think would indicate a definite tropo? 100 miles?

You would think FM BC DX would be all over the radio, I haven't ever seriously checked that out although I've heard New Jersey FM just casually noted.